When Tom shows up with some of his friends on horseback, Gatsby is asked to join them. Through the course of the conversation, Gatsby informs Tom that he has met his wife (Daisy) before. Tom is suspicious and wonders where he's met Daisy before. When Gatsby leaves, presumably to get his car keys, Tom remarks:

I wonder where in the devil he met Daisy. By God, I may be old-fashioned in my ideas, but women run around too much these days to suit me. They meet all kinds of crazy fish.

This is hypocritical because Tom "runs around" too much as well. He is having an affair with Myrtle. According to Tom's logic, he would be one of those "crazy fish." Tom is even quite open and even proud of this affair - with some people. In Chapter 2, he takes Nick to meet Myrtle as if to show off his ability to do whatever he wants. In his narrow-minded views, Tom accepts the double standard that women should not "run around" but that it is okay for men, namely himself, to do so.